Microfluidic applications sometimes require high pressure operation such as in the area of high performance liquid chromatography (HPLC). Microfluidic chips with integrated HPLC columns such as described in U.S. Pat. No. 5,500,071, incorporated herein by reference, have become popular in mass spectrometer applications. Typically, micromachined polymer columns are used for integrated HPLC columns, typically comprising two to five micromachined polymer sheets. However, the upper limits on pressure for typical polymer materials may limit their use for some application areas. Replacing typical polymer materials with type 304 stainless steel allows significantly higher pressure applications but type 304 stainless steel typically does not have the comparatively good micromachining techniques that titanium has associated with it.